Ultra-high hydrogen storage capacity of Li-decorated graphyne: A first-principles prediction

Abstract

Graphyne, consisting of sp- and sp2-hybridized carbon atoms, is a new member of carbon allotropes which has a natural porous structure. Here, we report our first-principles calculations on the possibility of Li-decorated graphyne as a hydrogen storage medium. We predict that Li-doping significantly enhances the hydrogen storage ability of graphyne compared to that of pristine graphyne, which can be attributed to the polarization of H2 molecules induced by the charge transfer from Li atoms to graphyne. The favorite H2 molecules adsorption configurations on a single side and on both sides of a Li-decorated graphyne layer are determined. When Li atoms are adsorbed on one side of graphyne, each Li can bind four H2 molecules, corresponding to a hydrogen storage capacity of 9.26 wt. %. The hydrogen storage capacity can be further improved to 15.15 wt. % as graphyne is decorated by Li atoms on both sides, with an optimal average binding energy of 0.226 eV/H2. The results show that the Li-decorated graphyne can serve as a high capacity hydrogen storage medium.

Decorated graphyne and its boron nitride analogue as versatile nanomaterials for CO detection

“…Previous studies have shown that the decorated metal preferentially adsorb on the centre of H sites [12,46]. Accordingly, in this work, we have decorated the GY and BN-yne with a Li or Ca atom centred on the H hollow site.…”

Lithium-decorated oxidized graphyne for hydrogen storage by first principles study

“…In Hongyu Zhang's work, the average binding energy is 0.24 eV when five H 2 is adsorbed. 33,35 It can be found that the binding energy of H 2 is relatively higher in Li-OG system. As a control, the binding energies of Ti on graphene and graphene oxide are reported to be 1.40 eV and 4.99 eV, 5,12 indicating the enhancement of metal's binding energy by oxidization is ubiquitous.…”

“…The relaxed distances between H 2 and Li atom range from 2.0 Å to 3.0 Å , which is close to others' works. 16,33,35 The average binding energy between hydrogen molecules and Li atoms is defined as…”

“…30,31 Li-graphyne system and Cagraphyne system are designed based on c-graphyne, and the results show that these systems can reach extremely high storage densities. [32][33][34][35][36][37] However, the reported binding energy (1.35 eV) of Li atom is relatively small.…”

Tuning Hydrogen Storage in Lithium‐Functionalized BC2N Sheets by Doping with Boron and Carbon

“…Early transition metal (Sc, Ti and V)-decorated nanostructured materials can yield high adsorption energies of approximately 0.2-0.6 eV, [46][47][48][49][50][51][52][53][54][55] owing to the Kubas interaction, [56] which stems from the hybridization of H 2 s or s* orbitals with transition metal d orbitals. [60][61][62][63][64][65][66][67][68][69] Among the alkali metals, Li seems to be promising, as not only is it the lightest metal in the periodic table, but it also has a high capacity for storing H 2 molecules with moderate adsorption energy ( % 0.2 eV). [57][58][59] Transition-metal-clustered nanomaterials are highly reactive, and as such the first H 2 molecules dissociate.…”